1. Technical Field
The present disclosure generally relates to servicing a wellbore. More particularly, this disclosure relates to servicing a wellbore with calcium aluminate cement compositions comprising a fluid loss additive and methods of making and using same.
2. Background
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid, a string of pipe, e.g., casing, is run in the wellbore. The drilling fluid is then usually circulated downward through the interior of the pipe and upward through the annulus, which is located between the exterior of the pipe and the walls of the wellbore. Next, primary cementing is typically performed whereby a cement slurry is placed in the annulus and permitted to set into a hard mass (i.e., sheath) to thereby attach the string of pipe to the walls of the wellbore and seal the annulus. Subsequent secondary cementing operations may also be performed.
Wellbore servicing fluids are often modified to allow them to function for their intended purpose under extreme conditions (e.g., high temperatures/pressures, acidic environment). At high static subterranean temperatures, and in the presence of brines containing carbon dioxide, conventional hydraulic cements rapidly deteriorate due to alkali carbonation. Thus, the use of conventional hydraulic cement compositions in these types of environments may result in the loss of wellbore integrity. An alternative to conventional hydraulic cements when cementing in challenging environments such as steam injection wells or steam production wells is a calcium aluminate cement (CAC). The higher temperature resistance of a CAC when compared to Portland cement/silica mixtures is an advantage for long term integrity of the cement sheath. The use of a CAC offers many advantages as they provide in addition to high and low temperature resistance, resistance to sulfates, corrosion, and sour gas. Additional examples of wellbore servicing operations that typically employ CACs include the servicing of geothermal wells or carbon dioxide injection wells. CACs combined with a soluble phosphate salt, for example sodium metaphosphate, and a pozzolanic material such as Class F fly ash form quick setting CACs that upon setting bind well to the subterranean formation and to itself and display desirable mechanical properties such as high strength, carbonation resistance, low permeability, and improved corrosion resistance. A variety of CACs are commercially available with varying alumina contents.
High alumina cement compositions are best suited for cementing wells exposed to either elevated temperatures and/or acidic environments (for example, CO2 environment). A challenge to the use of such cements has been that conventional fluid loss agents may exhibit reduced effectiveness as the alumina content of the CAC increases. An ongoing need exists for fluid loss control additives in compositions comprising CACs.